In general, it is easier to protect a person from extremely low temperature environments than it is to protect a person from extremely high temperature environments. A person's body is a source of heat appropriately distributed by the person's circulatory system and thus, if the person's body is protected throughout against excessive heat loss to the environment, normal bodily functions can be maintained indefinitely.
From earliest recorded history, mankind has developed effective protective clothing for avoiding excessive heat loss to extremely cold environments by insulating the person's body from its environment. However, a person's body does not include any cooling source independent of its environment and thus mankind has not been as successful in developing protective clothing for avoiding excessive heating of a person's body in an extremely high temperature environment. For this reason, the preferred embodiments of this invention as shown in the drawing and described herein are specifically directed to the lowering of the temperature of a person's body below that which it would normally have in the environment to which it is exposed.
However, it will be understood that by simply providing the system of this invention with a source of heat rather than a source of cold, the temperature of a person's body could be raised to a temperature above that which it would normally have in any environment to which it is exposed. This might be done for therapeutic purposes in a normal environment, for example, as well as for maintaining normal body temperature in an extremely cold environment.
Three basic personal cooling systems have been proposed in the prior art. The first and least successful of these is to attempt to insulate the person's body from its environment by means of garments and then provide a source of cold within the garment such as blocks of ice, for example. Such a system is extremely uncomfortable for the user because of the great temperature differential between normal body temperature and the source of cold. In addition, the source of cold must be replenished at relatively short intervals requiring the opening of the garment and exposure of the person to the environment. Most importantly, such a system not only inactivates the normal cooling functions of the body through evaporation of perspiration but turns it into a disadvantage since the unevaporated perspiration will add to the discomfort of the user of such a system.
Thus, a second system was developed in the prior art based on attempts to augment the normal cooling functions of the body. One such approach is to place porous insulating garments in contact with the skin in an attempt to enhance the evaporation of perspiration and to augment the resulting cooling further by dampening the porous garment separately from perspiration. More sophisticated systems have included the circulation of air through the garment to enhance the evaporation and in some cases, the air has been cooled in an attempt to provide air conditioning as well as to enhance the evaporative cooling.
Again, such systems are extremely uncomfortable to the user since they tend to overpower the normal bodily functions of the user, producing unnatural conditions requiring excessive fluid intake by the user and discomfort at the skin and extremities, as well as loss of body fluids and salts.
More recently, liquid cooling loops have been proposed in which an attempt has been made to couple more directly to the normal circulatory system of a person's body. In such systems, heat exchange garments made of flexible material with liquid coolant passageways formed therein are placed in direct contact with the body of the user and liquid coolant is circulated through such garment. Insulating garments may be worn over the heat exchange garments and an attempt is made to cool the entire body of the user by circulating a cooled liquid through the liquid coolant passageways. Again, discomfort to the user has resulted from the tendency of such systems to overpower the normal cooling functions of the human body. The liquid coolant circulated is generally at a given temperature considerably below normal body temperature providing an excessive cooling effect in the extremities and a resultant upsetting of the normal circulatory system of the user. The upsetting of the normal functions of the circulatory system of the user may result in perspiration in parts of the body and excessive cooling at other parts of the body.
It is the principal object of applicant's invention to overcome the abovementioned disadvantages of the prior art by improved coupling of an external temperature source to the normal circulatory system of the user's body while preserving the normal bodily functions of the user and reducing the temperature differential between the user's body and the coolant.